1. Field of the Invention
The present invention relates to a gumming device.
More specifically, the present invention relates to a gumming device of the type comprising a frame; a gumming roller fitted to the frame to rotate about its own longitudinal axis, and presenting a substantially cylindrical outer surface for receiving an adhesive substance; supply means for feeding the adhesive substance on to said outer surface; and a scraping device comprising a scraper element substantially contacting, and for removing the adhesive substance from, said outer surface.
2. Discussion of the Background
Devices of the above type are described, for example, in U.S. Pat. Nos. 3,991,708, 3,996,890 and EP-A-O 534 664, in which the scraping device is connected directly to a tank or cavity facing and closed by the outer surface of the gumming roller and housing a given quantity of adhesive substance, and the scraping device defines one end of the tank and forms a sealing element, fixed or movable in relation to the tank, between the tank and the outer surface of the gumming roller.
Known gumming devices of the above type, wherein the scraping device substantially forms a portion of the tank, have proved critical at high operating speed, due to vibration of the tank resulting in corresponding vibration of the scraping device and hence in uncontrolled quantities of adhesive substance being emitted from the tank, and due to the scraping device controlling the emission of adhesive substance, as opposed to the quantity of adhesive substance already emitted from the tank. In other words, the scraping device acts as a poorly controllable tap for supplying the adhesive substance from the tank, as opposed to a precision device for controlling the thickness of the adhesive substance already fed on to the outer surface of the gumming roller.